This project will assess the speech, language, and sign skills of young cochlear implant users, and the complex inter-relationships that exist between abilities. In a new line of inquiry, we will examine the language development of children, and compare patterns of improvement to those of normal hearing children. We will relate pre-implant language performance measures and post-implant language patterns to post-implant gains in speech and listening. Using a multidimensional test battery, we will study speech production and determine whether gains continue and/or plateau after prolonged implant experience, and parse out factors that account for variability in performance. The relationship between speech production and speech perception performance will be studied, and these findings will be related to models of auditory feedback. We will also conduct a device- on/off experiment to further assess how on-line feedback affects the moment-to-moment regulation of articulatory behavior. A set of investigations will address the sign skills of children and relate them to emerging speech and language performance, and word coding and recall. The results of these experiments will illuminate processes of sign acquisition, and address concerns of members and advocates of the Deaf Community. Finally, a clinical study will be conducted in which we will assess whether measures of mismatched negativity can be used to select appropriate goals for auditory training. These results potentially will have widespread implications for remediation strategies for hard-of- hearing children.